A preparation method for a colon-targeting preparation, which uses ordinary capsules, fills colonic administration into the capsules, seals the capsule shell with a sealing material to form a liquid hard capsule, and uses colon The enteric coating solution is used for coating; the colon enteric coating solution is prepared by mixing coating materials, coating solvents and plasticizers; the filling in the capsule can be medicine for treating ulcerative colitis or colon cancer. The advantages of the present invention: the liquid hard capsule is coated with a pH-sensitive coating material to achieve the purpose of targeted release in the colon, and the ordinary gelatin capsule shell is used. Compared with the special colostomy-coated capsule shell of the prior art, the rate of loading is high. The coating process is stable, easy to operate, and suitable for large-scale industrial production; the liquid hard capsule prepared by this method can maintain the color and transparency of the original capsule after coating, and improve patient compliance; the process is simple, no special equipment is required, easy to operate, and low cost. low.